Background: Collecting duct carcinoma (CDC) is a rare type of renal cell carcinoma (RCC) originating from the renal medulla. Clinical outcomes are poor, and there are no consensus guidelines to guide therapy.
Objective: To determine genomic alterations (GAs) in a series of patients with locally advanced or metastatic CDC for whom genomic profiling was performed during the course of clinical care.
Design, setting, and participants: Formalin-fixed, paraffin-embedded blocks or slides were obtained for 17 patients with CDC. DNA was extracted and comprehensive genomic profiling was performed in a laboratory certified under the Clinical Laboratory Improvement Amendments.
Outcome measurements and statistical analysis: Bayesian algorithms and local alignment algorithms were used to detect substitutions and insertions/deletions, respectively. A comparison to normal control samples was used to detect copy number alterations. Clinically relevant GAs (CRGAs) were defined as those linked to approved or investigational targeted therapies.
Results and limitations: The median age in the cohort was 53 yr (range 26-73), and 14 primary tumors and three metastatic sites assessed. A total of 36 GAs were detected in this series of patients, with an average of 2.1 GAs per case. The most common GAs were in NF2 (5/17, 29%), SETD2 (4/17, 24%), SMARCB1 (3/17, 18%), and CDKN2A (2/17, 12%). Of nine cases assessed for FH GAs, two patients had FH homozygous loss. A limitation is that targeted interrogation of genes known to be implicated in other cancers was performed, so mutations outside of these cannot be excluded.
Conclusions: Recurrent CRGAs were detected in this series of CDC cases and suggest a possible benefit from targeted therapy. In particular, mTOR inhibitors may be of interest in patients with NF2 alterations. Alterations in FH and SMARCB1 also occurred in a mutually exclusive manner to NF2 alterations.
Patient summary: This report provides important genomic insights into collecting duct carcinoma, a rare type of renal cell carcinoma with a very aggressive course. These insights could further rationalize the use of targeted therapies for rare tumors according to the individual genomic alterations harbored.
Keywords: Collecting duct carcinoma; Genomic profiling; Medullary carcinoma; NF2.
Copyright © 2015 European Association of Urology. Published by Elsevier B.V. All rights reserved.